Nasa's mission to Jupiter is due to crash and burn on Sunday, but it has already given us the perfect excuse to head back to the giant gas planet. Launched in 1989, the spacecraft's greatest achievement was discovering an ocean deep beneath the icy crust of Europa, one of Jupiter's moons. Forget Mars - if there is life elsewhere in our solar system then the smart money says we will find it in the watery depths of Europa.

This is the main reason why Nasa has now steered Galileo into a fatal collision course with Jupiter itself. The probe is virtually out of the fuel that is needed to steer it and scientists were worried that if they lost control of Galileo it might crash into Europa, possibly contaminating the moon with Earth bacteria stowed away all these years.

"We could have lost control of it and it could have gone anywhere," says Paul Fieseler, a Nasa scientist working on the Galileo mission. "It's run out of gas, it's run out of power and it's just getting old."

Galileo will at least go out in a blaze of glory. Currently heading directly towards Jupiter at about a million miles a day, the probe will begin to feel the heat and pressure of the Jovian atmosphere at around 8pm our time on Sunday evening. "It will burn up and parts will undoubtedly break off. The spacecraft will be crushed, burned, melted and eventually evaporated," Fieseler says.

The probe could continue sending data about the planet back to Earth until about six minutes before the scheduled impact when, with just a hint of anticlimax, it will lose contact with the Earth as it passes around the far side of Jupiter.

Galileo is already living on borrowed time. It proved to be so productive that Nasa scientists extended its intended mission lifetime three times. It suffered a high-profile problem when a radio antenna stubbornly refused to work, but has confounded expectations since then. "This little spacecraft has survived about four times the amount of radiation it was ever designed to take," Fieseler says. "Every time something knocked it down it got back up again."